The present invention relates generally to the braking system of a bicycle, and more particularly to the balancing structure of brake cables hoisting seat of a bicycle.
As shown in FIGS. 3 and 4, the braking system of a conventional bicycle comprises a V-shaped cable-hoisting seat 1 and two linked brake seats 2 and 2'. Located in one wing of the cable-hoisting seat 1 is a fixed end 12 provided with a cable hole 121 in which a steel brake cable 13 is received securely. The brake cable 13 is fastened at one end thereof with the brake seat 2'. Located in another wing of the cable-hoisting seat 1 is an urging end 15 provided therein concentrically with an upper hole 151 and a lower hole 152, which have different diameters. The upper hole 151 is dimensioned to hold a sheathed fitting head 171 of another steel brake cable 16 which is received securely in the lower hole 152 and is fastened at one end thereof with another brake seat 2. As shown in FIG. 3, the steel brake cable 16 has a sheathed end 17 which is fastened at one end thereof with a brake lever. As the brake lever is triggered with hand, the brake seat 2 is caused to turn toward the rim 3 of the wheel 32 of the bicycle. In the meantime, the urging end 15 of the cable-hoisting seat 1 is caused to move downwards, thereby bringing about an upward movement of the fixed end 12 of the cable-hoisting seat 1. As a result, the brake seat 2' is caused to move toward the rim 3 of the wheel 32 of the bicycle. As the brake shoes 21 and 21' of the brake seats 2 and 2' are forced against both side edges 31 of the rim 3 of the wheel 32, the bicycle is brought to a halt.
The conventional bicycle braking system described above is defective in design in that the effect of the braking system is often undermined by the fact that both brake shoes 21 and 21' of the brake seats 2 and 2' often fail to make contact simultaneously with the rim 3 of the wheel 32. In addition, the cable-hoisting seat 1 and the brake seats 2 and 2' are fastened respectively to an upper support tube 42 and a lower support tube 41, which are welded to the fork tube 4. If the job of welding the lower support tube 41 and the upper support tube 42 is done poorly, the operation of the cable-hoisting seat 1 and the brake seats 2 and 2' can be further undermined.